Rediscovery and neotype designation of Dichaetura surreyi Martin, 1990 (Gastrotricha: Paucitubulatina) from Northern Germany with a threefold morphological examination with a specimen-saving method

The rediscovery of Dichaetura surreyi Martin, 1990 from farm ditches in Northwest Germany (East Frisia) provides new data on freshwater meiofauna. To gain the maximum amount of detailed morphological and anatomical data from the limited number of individuals, a specimen-saving methodology is employed, combining light microscopy, confocal laser scanning microscopy and scanning electron microscopy on the same specimens. This approach refined the taxonomic understanding of Dichaetura surreyi , confirming originally described morphological features, while complementing undescribed muscular architecture and cuticular characters for the Dichaeturidae family. Genetic data on mitochondrial COI locus is provided along a gene tree with members of Paucitubulatina, hinting at a close phylogenetic position to Polymerurus under Maximum Likelihood approach. The designation of a neotype and deposit of mitochondrial barcoding sequences establishes reference for future research, addressing gaps in knowledge surrounding this poorly known family and advancing understanding of freshwater meiofaunal diversity.